Frictional power transmission belts such as V-ribbed belts have been widely used as belts for transmitting power to auxiliaries in automobile engines and the like, for example. Recently, frictional power transmission belts have been increasingly used under high-tension and high-load environments, because the size reduction of engines has led to reduction in the number of ribs and the width of the belt, and because loads due to driving of auxiliaries have increased. For this reason, frictional power transmission belts are required to have a rubber having a high modulus and high tear resistance performance as an adhesion rubber located around a cord that is a tension member.
Conventionally, a V-ribbed belt used under a high-load environment is known in which a short fiber is included in at least a part of an adhesion rubber to provide a high modulus to the adhesion rubber, as disclosed in Patent Document 1. Here, an ordinary nylon or aramid fiber, or a modified nylon microfiber obtained by bonding polyolefin to a nylon fiber is used as the short fiber. In addition, for example, EPDM is used as a rubber component of the adhesion rubber to improve the heat resistance and durability.
Patent Document 1: Japanese Patent Application Publication No. 2007-198485